Clustered metallothionein genes are co-regulated in rice and ectopic expression of OsMT1e-Pconfers multiple abiotic stress tolerance in tobacco via ROS scavenging

Abstract

BackgroundMetallothioneins (MT) are low molecular weight, cysteine rich metal binding proteins, found across genera and species, but their function(s) in abiotic stress tolerance are not well documented.ResultsWe have characterized a rice MT gene, OsMT1e-P, isolated from a subtractive library generated from a stressed salinity tolerant rice genotype, Pokkali. Bioinformatics analysis of the rice genome sequence revealed that this gene belongs to a multigenic family, which consists of 13 genes with 15 protein products. OsMT1e-P is located on chromosome XI, away from the majority of other type I genes that are clustered on chromosome XII. Various members of this MT gene cluster showed a tight co-regulation pattern under several abiotic stresses. Sequence analysis revealed the presence of conserved cysteine residues in OsMT1e-P protein. Salinity stress was found to regulate the transcript abundance of OsMT1e-P in a developmental and organ specific manner. Using transgenic approach, we found a positive correlation between ectopic expression of OsMT1e-P and stress tolerance. Our experiments further suggest ROS scavenging to be the possible mechanism for multiple stress tolerance conferred by OsMT1e-P.ConclusionWe present an overview of MTs, describing their gene structure, genome localization and expression patterns under salinity and development in rice. We have found that ectopic expression of OsMT1e-P enhances tolerance towards multiple abiotic stresses in transgenic tobacco and the resultant plants could survive and set viable seeds under saline conditions. Taken together, the experiments presented here have indicated that ectopic expression of OsMT1e-P protects against oxidative stress primarily through efficient scavenging of reactive oxygen species.

A nuclear-localized histone-gene binding protein from rice (OsHBP1b) functions in salinity and drought stress tolerance by maintaining chlorophyll content and improving the antioxidant machinery

“…Seeds were then rinsed four times with sterile distilled water and sown on the germination medium, containing MS salts, 30g/l sucrose and 0.8% agar (pH 5.8). Fifteen days-old seedlings were used for transformation as reported earlier (Kumar et al, 2012). Presence of the transgene in the hygromycin-resistant seedlings was confirmed by PCR.…”

Towards Understanding Abiotic Stress Signaling in Plants: Convergence of Genomic, Transcriptomic, Proteomic, and Metabolomic Approaches

“…Nowadays, success has been achieved in genetic improvement of plants for better abiotic stress tolerance by manipulating the gene-encoding enzymes involved in the regulatory pathways (Kumar et al 2012 ).…”

“…Similarly, analysis of transcriptomes can also pave way towards isolation of "candidate genes" which would be suitable for raising transgenic plants with improved tolerance. In recent past, several publications have reported that using the comparative transcriptomic approach between contrasting genotypes of rice (IR64 and Pokkali), several differentially regulated genes could be isolated, which then served as useful genes in functional genomic studies (Kumari et al 2009 ;Karan et al 2009 ;Mustafa et al 2010;Kumar et al 2012 ;Soda et al 2013 ). It is also true that the analysis of changes in proteome of crop plants in response to abiotic stresses can also be used as a starting point to fi sh out the genes, which may ultimately serve as the "candidate genes" (Ruan et al 2011 ) In this chapter, we have described the various "omics"-based approaches, which have been employed in recent years to understand the response of plants towards abiotic stresses.…”

OsWRKY42 Represses OsMT1d and Induces Reactive Oxygen Species and Leaf Senescence in Rice

“…In RT-PCR analysis of the shoots of rice seedlings, three of these genes, lëjqN~, lëjqNÅ and lëjqNÇ, with high transcript levels were downregulated under salinity stress and ABA treatment, whilst they were previously found to be upregulated after drought stress (Kumar et al, 2012). This result suggests that these clustered lëjqN genes may be coregulated under certain stress conditions.…”

“…Senescence is controlled by multiple developmental factors and also external biotic and abiotic stress signals (Buchanan-Wollaston et al, 2005;Lim et al, 2007;Munne-Bosch and Alegre, 2004). Comprehensive analyses of altered gene expression patterns in genetically controlled senescent leaves, as a study model for plant senescence, has identified important regulatory factors.…”